According to the biological evolution principle of“survival of the fittest and elimination of the unfit”, the natural selection theory of“overbreeding, genetic variation, survival struggle and survival of the fittest”was applied to sexual hybridization, directional selection and quality improvement of rice. Through the wide collection of domestic and foreign genetic resources, the number of combinations was increased, the inferior combinations were eliminated in low generation（F₁）, and the superior combinations were selected. The individuals selected from the superior combinations were mixed and planted into a large group containing multiple genetic resources（F₂）. In the large group, the superior individual plants were selected according to the target characters and genetic type. In large groups, selected individual plants(F_3～5) continued to be planted in group form（or subgroups according to the type of target traits） or in the form of lines. In the process of purification of target traits, the best plants were selected until the traits were stable. By using this method, the high quality and high yield varieties“Tongxi103”and“Tongxi140”were selected and approved, and created a number of excellent resources as parents have be used. It has been found that this method is an effective method for breeding new varieties of rice by sexual hybridization and can achieve the breeding effect of selecting the best from the best.